Alternative Center Filters for Rodenstock 75/4.5 Grandagon N?

[acapela]

I came into a used Rodenstock 75/4.5 Grandagon N recently, but am without a "dedicated" center filter.

I can watch eBay for the original Rodenstock center filter (a 1.5-stop/3x in a 67-86mm size). But in the meantime (none appear to be listed at the moment), what might those with actual user experience recommend as a substitute?

I have Schneider 3b center filters already, for my 47/5.6 Super Angulon XL and 80/5.6 Super Symmar XL lenses. The 3b is a 1.5-stop/3x 67-86mm filter, so would be mechanically compatible and hopefully at least somewhat optically compatible as well.

I also have a source for new/old stock for Schneider "plain 3" (i.e. "III") filters, originally for use with the 65/5.6 and 75/5.6 Super Angulon, though I would have to buy one even just to test with it. Finally, I also see a Schneider "IIIa" filter for auction currently on eBay. I can't find any documentation on a 3a anywhere, but photos in the listing clearly show "IIIa" on the filter mount. I am assuming this actually a "plain 3/III", bearing a relatively recent cosmetic change in designation when additional variants of 67-86mm center filter ("IIIb/c/etc", for other Schneider lenses) reached the market.

Any actual user testimonials/advice would be welcome. In the meantime, my simplest option is to start with the 3b filter I actually have in hand and see if that is "good enough", even illumination, free of banding, etc.

Thanks.

[Oren Grad]

I would try the IIIb that you already have. In my occasional experience of center-filter-shopping, Rodenstock center filters have been much harder to find than Schneiders.

See also this thread:

http://www.largeformatphotography.in...IIb-difference

[acapela]

See also this thread:

http://www.largeformatphotography.in...IIb-difference

Aha, confirmation of the existence of the "IIIa", interesting. Sounds as if the IIIa is for "older" lenses, rather than the more recent XL/wide-field lenses.

Thanks!

[Bob Salomon]

The Heliopan is virtually identical to the Rodenstock.

[r.e.]

The Heliopan is virtually identical to the Rodenstock.

Thanks for this information. I'm looking to purchase a centre filter for this lens. It's helpful to learn that the Heliopan 67/86 and the Rodenstock 67/86 are interchangeable.

Re Schneider, David A. Goldfarb says this in another thread (boldface added):

"I've compared the III to the IIIb and the difference is 1/4 stop. I use the III on my 90/8 Super-Angulon, 75/4.5 Grandagon-N and 55/4.5 Apo-Grandagon.* There are times when I'd like a stronger center filter, but it's something of a subjective thing, since even the dedicated filters don't correct 100% for falloff. If they did, they would have to be darker than most people would tolerate."

That makes it sound like both Schneider centre filters will work, but that Goldfarb may prefer the "look" of the III, which he says also has slightly less of an exposure penalty. Re his last two sentences, Schneider does say in its literature that vignetting is not fully compensated, "to avoid too long exposure times and with consideration of the exposure latitude of the film emulsions".

Link to David Goldfarb's post: https://www.largeformatphotography.i...l=1#post244210

More generally... My impression, after reading a good number of threads on the subject of centre filters, is that the main reservation is their cost. As I understand it, I'll have to stop down this lens to at least f/9 for a centre filter to work mechanically/optically. Sounds OK to me. After that, the exposure compensation appears to be about 1 1/2 stops (Bob Salomon suggests in another thread that it may be 1 1/3 stops). Maybe it's because I shoot video, where neutral density filters are a fact of life, but I'm not terribly fussed about the penalty.

If I want to add further filtration, it appears to be a matter of experimenting with Lee100 square filters (100mmx100mm), which I have, and screw-in filters that are 86mm or, with an 86mm-95mm step-up ring, 95mm in diameter. The latter interests me as an option because I have a Nikkor-W f/6.5 360mm lens that takes 95mm filters.

The trick is finding a centre filter that's in good condition optically and that I can afford

If anybody has suggestions or views that differ from what's in this post, I'd love to read them.

* Dan Fromm's Schneider table in the following article would also appear to suggest the III: Center Filters for Large Format

[r.e.]

My impression, after reading a good number of threads on the subject of centre filters, is that the main reservation is their cost. As I understand it, I'll have to stop down this lens to at least f/9 for a centre filter to work mechanically/optically. Sounds OK to me. After that, the exposure compensation appears to be about 1 1/2 stops (Bob Salomon suggests in another thread that it may be 1 1/3 stops). Maybe it's because I shoot video, where neutral density filters are a fact of life, but I'm not terribly fussed about the penalty.

If I want to add further filtration, it appears to be a matter of experimenting with Lee100 square filters (100mmx100mm), which I have, and screw-in filters that are 86mm or, with an 86mm-95mm step-up ring, 95mm in diameter. The latter interests me as an option because I have a Nikkor-W f/6.5 360mm lens that takes 95mm filters.

I'm going to have a hands-on opportunity to assess whether a centre filter will be useful having regard to how I plan to use the lens. I expect to receive the Grandagon-N f/4.5 75mm later this week, and a participant in the forum has very kindly offered to lend me a Rodenstock 67/86 centre filter for a few days.

I plan to try out the lens, without and with the centre filter, with Ilford FP4+ 125, Kodak Portra 160 and Kodak Ektar 100. The characteristics of the two colour films are sufficiently different that I think that it's worth testing with both.

I don't have 86mm screw-in filters or a Lee100 86mm adapter. To see what happens when I add an additional filter, l'll set up a shot where I can handhold a Lee square linear polariser (to cut glare/reflections), or a Lee ProGlass IRND 2-stop neutral density filter.

As part of this, it would be useful to try some camera movement. I'll be using an Arca-Swiss F-line camera with a 300mm rail, 171mm standards and a recessed lens board. See the photo below. I'll be using a shorter bellows than the one in the photo, but I don't have a proper bag bellows. Don't know how much rise I'll be able to coax from the bellows with a 75mm lens, but I'll give it a go.

I may write a follow-up post about my conclusions.

Many thanks to the forum member who has offered to lend me the Rodenstock centre filter.

[Bob Salomon]

When using a polarizer on wide angle lenses outdoors it is important to remember that areas of the sky are naturally polarized and other areas are not. Using a polarizer while including both types of areas will result in banding in the sky.
Best is just test with the center filter and forget the polarizer. Just remember that for the center filter to be effective you must stop down at least 2 stops from wide open and add 1 ⅓ for the factor.

[r.e.]

When using a polarizer on wide angle lenses outdoors it is important to remember that areas of the sky are naturally polarized and other areas are not. Using a polarizer while including both types of areas will result in banding in the sky.
Best is just test with the center filter and forget the polarizer. Just remember that for the center filter to be effective you must stop down at least 2 stops from wide open and add 1 ⅓ for the factor.

Hi Bob, that's why I said that I'll use the polariser "to cut glare/reflections". I'm thinking shiny surfaces and shop windows. The last time that I used a polariser on the sky was with a 35mm camera and 24mm lens years ago in Wadi Rum in Jordan. Would have been great desert photographs were it not for the polariser. I hated the effect, and haven't repeated the mistake since

Anyway, this is just to test stacking, having regard to what I have in the Lee line.

Yes, my understanding is that I have to stop down this lens to at least f/9 for mechanical/optical reasons, plus add filter factor. I've seen suggestions that this lens is best at f/16 and f/22. Is that your view?

[Bob Salomon]

Hi Bob, that's why I said that I'll use the polariser "to cut glare/reflections". I'm thinking shiny surfaces and shop windows. The last time that I used a polariser on the sky was with a 35mm camera and 24mm lens years ago in Wadi Rum in Jordan. I hated the effect, and haven't done it since

Yes, my understanding is that I have to stop down this lens to at least f/9 for mechanical/optical reasons, plus add filter factor. I've seen suggestions that this lens is best at f/16 and f/22. Is that your view?

It is diffraction limited at f22.

[r.e.]

It is diffraction limited at f22.

Thank-you.


For those who are interested, Rodenstock has a link to its archived catalogue for analogue lenses and centre filters here: https://www.rodenstock-photo.com/service